This invention relates to a sheet feeding apparatus that separates and feeds single sheets into an image forming apparatus such as a copier or printing apparatus.
Many image forming apparatus such as copiers or printers comprise a sheet storage portion for storing sheets to form images such as characters or drawings thereupon and are provided a sheet feeding apparatus for drawing out one sheet at a time as required and for feeding them to the image forming portion.
The sheet storage portions in these sheet feeding apparatuses are formed to allow the storage of a variety of sheet sizes. The image forming apparatuses is made to input the size data of the sheets stored in the aforementioned sheet storage portion from the sheet feeding apparatus to perform a variety of controls such as checking the conformity of the original size and the sheet size and for setting the jam timer for detecting sheet jams in the sheet feed path.
The image forming apparatus has limits in being as compact as possible because it handles one or a plurality of sheets the sizes of which is prescribed by all types of standards, but there is always a great need to reduce the space required for image forming apparatus in offices, so it is necessary to reduce the size of image forming apparatus, particularly their footprint as much as is possible.
However, in conventional sheet feeding apparatuses, various types of sheet size detecting means are used to detect the size of sheets stored in the sheet storage portion.
In an example of the most common type of sheet size detecting means in the current technology, the sheet detecting means that is a mechanical detecting means such as an optical detecting means or limit switches are established the bottom surface of the sheet storage portion or in plurality below the image forming apparatus to detect the size of the sheets stored in the sheet storage portion (the first prior art example).
Another example is when a sheet feeding apparatus comprising a sheet storage portion is installed in a prescribed sheet feeding position inside the image forming apparatus, a sheet detection means mounted on the image forming apparatus frame side for storing the sheet feeding apparatus detects the size of the sheets stored in the sheet storage portion (the second prior art example).
However, in the aforementioned first prior art example, depending on the set docking position of the image forming apparatus and the sheet feeding apparatus, the relative position of the sheet size detection means with regard to the sheet differs causing the problem of not being able to accurately detect the size of the sheets.
Also, in the aforementioned second prior art example, because the sheet detecting means is mounted to the frame of the image forming apparatus that stores the sheet feeding apparatus, the size of the footprint of the image forming apparatus necessarily must be enlarged that much.
An object of the present invention is to provide sheet feeding apparatus comprising a sheet storage portion that can store a variety of sheet sizes and that can accurately detect the size of the sheets that are stored therein and that has a more compact apparatus size.